Should I make the call to check up on the status of my app. even if an interviewer stated he would call?

I had an interview last week and was told by the interviewer that they will call me today, specifically Friday, to notify me about my status, whether I had been selected or not. I have had a bit of a rocky job search and interview process, and it has made me quite anxious. I know the company office closes at 6:30pm. Do you think that once it's 5:00pm and there is still no call, that I should give them a ring? I should hate to go through a weekend in agonizing anticipation of the results.